/*
struct ListNode {
    int val;
    struct ListNode *next;
    ListNode(int x) :
            val(x), next(NULL) {
    }
};*/
class Solution {
  public:
    ListNode* FindFirstCommonNode( ListNode* pHead1, ListNode* pHead2) {
        if (pHead1 == nullptr || pHead2 == nullptr) return nullptr;
        ListNode* cur1 = pHead1, *cur2 = pHead2;
        while (cur1 != cur2) {
            cur1 = cur1 != nullptr ? cur1->next : pHead2;
            cur2 = cur2 != nullptr ? cur2->next : pHead1;
        }
        return cur1;
    }
};
